1. Field of the Invention
The invention relates to a water-vapor plasma torch for cutting a workpiece, comprising a feed line for a liquid, a heating device, and an evaporator for forming a gas from the liquid, a cathode detachably connected to a movably mounted piston rod, and a nozzle with an outlet opening for the gas.
The invention further relates to a method of detecting the wear of the cathode of a water-vapor plasma torch during and after a cutting process, with said cathode being detachably connected with a piston rod, wherein the heat generated by an electric arc is thermally coupled into the piston rod connected with the cathode so that when the temperature changes at the cathode, the temperature within the piston rod will also change.
Moreover, the invention relates to a method of detecting the wear of the anode of a water-vapor plasma torch, said anode being designed as a nozzle with an outlet opening, wherein a gas escapes through the outlet opening formed by evaporation of a liquid, fed via a feed line, by means of a heating device, and an evaporator, wherein the nozzle is worn out by enlarging the outlet opening, thus increasing the flow rate of the liquid.
Likewise, the invention relates to a method of controlling a cutting process conducted by means of a water-vapor plasma torch, wherein a liquid is fed to the torch via a feed line, and wherein the liquid is evaporated into a gas by means of a controlled heating device and an evaporator.
2. The Prior Art
From the prior art, in particular from EP 1 522 371 A1, it is known to arrange a plurality of sensors in a plasma torch which detects the temperature or voltage, e.g. Here, the individual sensors are connected to a processor in the plasma torch which, in turn, is connected to the processor in the current source via a data line. Thus, the cutting process can be controlled based on the measurement values provided by the sensors.
Here, it is disadvantageous that the size of the plasma torch increases with each sensor installed therein, and with the integration of the processor and the electronics associated therewith. This makes the handling of the plasma torch at least partially more difficult. Likewise, the risk of interference is increased by using sensitive electronics in the plasma torch. Furthermore, no technical solution for wear detection is described in EP 1 522 371 A1.
Moreover, it is known from the prior art to control the temperature of an evaporator, which evaporates liquid, in a torch of a water-vapor cutting device.
Here, it is disadvantageous that the heat introduced into a cathode via the electric arc may influence the temperature control of the evaporator in an unpredictable manner since the heat introduced by the cathode is not taken into consideration when controlling the temperature of the evaporator. Thus, the torch may possibly be overheated and destroyed.